• Title/Summary/Keyword: Sintered Powder

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Multi-pole anisotropic Sr-ferrite sintered magnets fabricated by powder injection molding (분말사출성형으로 제조된 다극 이방성 Sr-페라이트 소결자석)

  • Cho, Tae-Sik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.284-287
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    • 2001

  • Multi-pole anisotropic Sr-ferrite sintered magnets has been studied by powder injection molding under applied magnetic field. The orientation of anisotropic Sr-ferrite powders higher than 80% during injection molding is achieved at the following conditions; apparent viscosity lower then 2500 poise in 1000 $sec^{-1}$ shear rate and applied magnetic field higher then 4 kOe. For the high fluidity and strength of injection molded compact, and the effective binder removal without defects during solvent extraction and thermal debinding, the optimum multi-binder composition is paraffin wax(PW)/carnauba wax(CW)/HDPE = 50/25/25 wt%. The rate of binder removal is proportional to the mean particle size of Sr-ferrite powders whereas it is inversely proportional to the content of Sr-ferrite powders and the sample thickness. The high magnetic properties of Sr-ferrite sintered magnets are; 3.8 kG of remanent flux density, 3.4 kOe of intrinsic coercivity, and 1.2 kG of surface flux density (l-mm-thick) in the direction of applied magnetic field.

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Effect of Mixing Method of Sintering Additives on the Sintered and Mechanical Properties of $Si_3N_4$ (질화규소의 소결 및 기계적 특성에 미치는 소결첨가제 혼합방법의 영향)

  • Kim, Ji-Soon
    • Analytical Science and Technology
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    • v.6 no.2
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    • pp.207-215
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    • 1993

  • $Si_3N_4$ powders were mixed with sintering additives($3Y_2O_3{\cdot}5Al_2O_3$, YAG) by coprecipitation method. Mixing homogeneity, sintered and mechanical properties of coprecipitation-mixed powder compacts were compared with those of mechanically-mixed ones. SIMS-analysis for composition on the surface and in the matrix of prepared powder mixtures showed that the added YAG exists mainly on the $Si_3N_4$ powder surfaces in a form of coating. From this result it could be concluded that coprecipitation method is superior to mechanical mixing in the mixing homogeneity. This mixing homogeneity can accompany an improvement in sintered density, microstructure and consequently the mechanical properties of sintered bodys.

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